Getting A Firm Grip With An IRS Cobra Thanks To Steeda's G-Trac Suspension.

When Ford announced that its top Mustang, the SVT Cobra, would get a genuine IRS rear suspension in 1999, the news sent shockwaves throughout the automotive community. While drag racers winced and immediately figured out ways to retrofit a solid-axle 8.8 underneath, autocrossers and open-track fiends finally had their prayers answered with a suspension package that featured robust aluminum lower control arms, forged steel uppers, and adjustable toe links, all wrapped around an aluminum differential that used conventional 8.8 gears. It was a match made in heaven. Well, at least on paper.

When we took our first turn behind the wheel of a pre-production car back in late 1998, we ran it through its paces and it didn't take long to realize something was amiss. Aside from noticeable wheelhop, we quickly concluded that the IRS was lacking in response, predictability, and more importantly, traction, while applying power in a turn. After a few '99 Cobras fell into the hands of several twisty turney racers, the same conclusion was quickly made.

Luckily, Ford heard the cry and in 2003, coinciding with the launch of the much-more-powerful Terminator, it beefed up the IRS. Aside from larger 31-spline axleshafts, the biggest change was the addition of specific rate springs and aggressively tuned Bilstein shocks to control wheel movement. Going up to 17x9 wheels and 275/40/17 tires also helped, but its inherent design was still flawed. Despite the changes that Ford made, it still didn't feel right as the car felt somewhat disconnected when driven hard.

Fast forward to 2008, and we've witnessed a huge step in making IRS Cobras finally work. There are a few companies making suspension components for the '99-'04 IRS Cobras, but based on our experience, few have put together a kit that is comfortable enough for the daily grind, yet competent enough for the track, as well as Steeda has. Now we all know that Steeda is no newcomer to the Mustang suspension market, but when it comes to manufacturing its own suspension upgrades, going to Steeda is like coming home, as you know that you'll get OEM-type fit, finish, and quality.

Getting On StageFor '03-'04 Cobras, Steeda offers three different G-Trac suspension systems-Street, Competition, and Drag. Since we wanted a more aggressive ride without excessive harshness, we kept things realistic and chose not to put a full-blown competition suspension into our Snake, as it was simply overkill for our weekend play toy. In addition, with our focus on handling, we found no need to go with a dedicated drag suspension because this car has already been running strong with a best of an 11.92 at 118.9 mph.

So, of these three choices, we went with the Street kit, which has components bundled into four complementing stages that allow a Cobra owner to install each stage separately. For instance, you can start with Stage 1, and then add Stage 2 and Stage 3 later. Then if you wanted to, you could finally put Stage 4 in the car a few months down the road. Or you can order all four stages at once, and a complete suspension upgrade can be performed at one sitting, which is how we did it simply because of deadline restrictions.

Starting with Stage 1 (PN 555-2155), we stiffened up our ride with Steeda's boxed steel subframe connectors, three-point tubular steed strut tower brace, billet aluminum caster/camber plates, and Sport Springs, which lower the car a little over an inch. This is often where many people start and serves as the "gateway drug" to better handling and fun on the street.

We then stepped up to Stage 2 (PN 555-2156), which features Steeda's polyurethane IRS subframe and differential bushings, steering rack bushings, heavy-duty antisway bar endlinks, front sway bar bushings, and superfly billet sway bar mounting brackets. For the upper rear subframe mounts, the included reinforcement kit will eliminate a lot of flex that goes on back there.

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Also included are Steeda's innovative anti-bumpsteer kit (which relocates the pivot point of the outer tie rod so that toe angle does not change during compression of the front suspension) and Steeda's trick X2 lower ball joints. Now, you may be wondering what role a lower ball joint has in improving handling, but it's pretty cool how the X2 piece works. With the stock ball joint, control arms can pivot too far up into the car and track width, camber angle, and even the toe changes, which can make handling quite unpredictable. By extending the shank portion of the ball joint (like the X2 does), though, the outer ends of the control arms sit further down and make the arms themselves sit more parallel to the road, allowing them to work within its original range of motion for improved suspension response and proper geometry. Appropriate spring spacers are included to compensate for the vehicle height that would have been lost if one installed the X2 ball joints alone.

Moving up to Stage 3, PN 555-2157, you'll benefit from world-class Bilstein dampers all around, which are an improvement to even the original Bilsteins that came from the factory on all '03-'04 Cobras. Next up is Steeda's own lower G-Trac brace that ties the rear of the front crossmember together for improved rigidity. It should be noted that a lower brace was installed at the factory, but the Ford piece is a stamped steel unit that is crush-bent and does not offer as much reinforcement as the Steeda piece, which is a straight tubular steel bar. Lastly, Steeda's innovative 1.375-inch tubular front antisway bar with spacer kit rounds out this stage.

Once you're at Stage 4, you've reached Steeda's pinnacle for street-ready IRS Cobra competence. To complete Steeda's suspension upgrade for Terminator Cobras, PN 555-2158 includes a steel IRS differential cover brace, polyurethane bushings for the rear control arms, and offset front control arm bushings for more caster and subsequently, more camber gain as the wheel is turned. Lastly, a solid steering shaft, supplied by Flaming River, tightens up steering response at the wheel and provides more immediate feedback to the driver.

Not wanting to leave all of our mods on a set of worn tires, we chose to upsize with 18-inch shoes. Since we were on a street theme, rather than a track-only setup, we elected to go with Steeda's own Pentar wheel in 18x9.5-inch sizing, wrapped in Nitto's grippy INVO tires, measuring 275/35/18 all around. These rather new tires are designed for high-end exotic cars, so we felt confident they would be perfect for our top Snake.

As installation was a simple R&R, not too many special tricks were required. We were able to do everything in our own home garage with a generous selection of mechanics tools and plenty of patience. It should be noted that suspension service can be dangerous for the inexperienced mechanic, and we recommend having someone who knows their way around the underpinnings of a Mustang to be by your side. Sadly, I've done nothing but resurrect rotten old Fox and SN-95 Mustangs from the brink of extinction for the past 15 years, so I'm a rather experienced Mustang suspension meck-a-nik, which can be fortunate for this story (or unfortunate, depending on how you look at it).

G-Trac TestingTo catapult this Cobra around Raceway Park's road course (in its shorter configuration) we relied on the driving services of Chris Winter, the manager of the track and owner of Crazy Horse Racing. Aside from being able to give us repeatable numbers, his experience on this track with Mustangs would be very valuable. He also gave us candid feedback on how the suspension performed both before and after the Steeda components (for detailed driving impressions, see sidebar).

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We baselined our Cobra with a 1:24.77 lap time and were able to pound down some rather strong and consistent supporting numbers. Due to our Cobra's relatively weak factory-stock cooling system, we were able to only get four laps before the engine management system began taking timing and rpm out from the excessive engine temp.

A few weeks later, we went back armed with our new suspension. Using the exact same tire pressures, track configuration, and driver, we'd be able to see exactly how much better our car would handle.

After one warm up lap, Chris dove into the Cobra's deep torque curve and quickly applied the power from turn to turn, posting three times that were eerily consistent: 1:18.92, 1:18.55, and 1:18:03, all of which were improving as he went along. Like last time, the engine began running too hot for the EEC-V's comfort, and any throttle input resulted in a rev limiter that sounded like the traction control was on in the burnout box. Despite laying down just four laps, we were able to record a solid 6.74-second improvement.

Like in drag racing, having nearly seven seconds shaved off your time on a road course that is over a minute long is like an eternity. As Chris mentioned, "The suspension is night and day. It gets more power to the ground in the turns and relies on the tires for more grip, whereas the stock suspension gave up before the tires did. Put an R-compound tire on this car and you're talking serious numbers."

Afterwards, I then strapped myself into the car to see what he was talking about. Without a doubt, he hit everything right on the head. When the car was stock, it felt top-heavy and wallowed. Also, in slower turns, the rear always felt disconnected, as the inside wheel would never put the power down, no matter how hard the 8.8's diff tried.

With the Steeda suspension, however, the rear stayed planted under power, and more impressively, would rotate slightly under deceleration in a turn. In higher-speed sweeping turns, the car was much more stable, eliminating the stock suspension's tendency to gyrate under full acceleration.

Getting power from a Terminator is so easy most people don't need to spend more than a few hours of wrench-turning to make 500 hp. But getting that power to the ground on the street, well, that's a whole other part of the equation. Sure, one can build an 1,100 rwhp car for the dyno and spin tires in Fifth gear for Internet junkies to watch online, but we'd rather have our 453 rwhp and use every one of them everywhere we go. Thanks to Steeda, we now can.

Tire TestingFor our track test, we relied on the capable hands of Chris Winter to drive our Cobra test vehicle. If his name sounds familiar, it's because he's popped up several times in our magazine as the proprietor of Crazy Horse Racing in South Amboy, New Jersey. When not busy running his Dynojet, he spends his time at Raceway Park's road course managing its layout and accommodating the needs of all racers. In his free time, he's an avid road race junkie that instructs for the PDA, the Performance Drivers Association (www.pdadrivingschool.com).

So with our Cobra in his capable hands, Chris gave us the skinny on how the car fared with both the stock suspension and the 18-inch Nitto INVO tires compared to the NT-555 tires that were mounted on the stock Cobra wheels. When the car was stock, he complained about the amount of slop and how impossible it was to apply power anywhere in a turn. In transitions, the stock suspension was not liking it, as side-to-side weight transfer was quite pronounced. As for the tires, he mentioned that the NT-555 tires made the Cobra have more understeer, but the INVOs transformed the predictability of the car as it had a more approachable limit. Once at that limit, the tires did not bite you back if you were in a slide. Interestingly, Winter was quicker on the smaller NT-555s, which are more competition bred with its 260 treadwear.

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With the full Steeda suspension in place (G-Trac Street, Stages 1 through 4), we let Winter back on the track, and as expected, he was 6.74 seconds quicker using the NT-555 tires. The drastic time drop was easy to see as the car simply hooked and went. As he states, "In certain areas, I was as much as 15 mph faster because I was able to plant the power fully and earlier in the turns without the car being unstable. That made the biggest difference, in addition to the flatter cornering in the faster turns."

Our subsequent follow-up drive on the road course backed his comments and reinforced our belief in leaving track driving for the track. But later, the ultimate test was on the street where we could see how it was to live with the new suspension. The ride is slightly stiffer than before. We'd say the ride is about 10-15 percent firmer. The car now has a more aggressive stance that not only looks the part, but also acts the part with incredible stability on the highways and byways.